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A
"very great" earthquake struck the
North Indian Ocean & the Bay of Bengal at 00:58 UTC on 26 December
2004. The earthquake began near the island
of Simuelue off the west coast of Sumatra and ruptured a
1,500-kilometre section of the boundary between the Indian Plate &
the Burmese Microplate. Shaking from the earthquake
was felt many parts of south Asia and Indo-China.
A devastating Indian Ocean-wide tsunami
was generated by this earthquake causing heavy
fatalities in many countries surrounding the Indian Ocean basin.
This event is also referred to as the "Boxing Day Tsunami
and/or Earthquake", "The Asian Tsunami
and/or Earthquake and the "Indian Ocean Tsunami".
2,30,210
people were are
estimated to have been killed in the Indian
Ocean-wide tsunami generated by this earthquake (from
Wikipedia); 1,84,168 of these were confirmed and 45,752 were
missing. The highest death toll was from
Sumatra where 1,30,736 persons were confirmed dead. This was
followed by Sri Lanka where 35,322 fatalities were confirmed. 12,504
deaths were confirmed in India, 5,395 in Thailand, 82 in the
Maldives, 78 in Somalia, 69 in Malaysia, 61 in Myanmar, 10 in
Tanzania, 3 in the Seyschelles, 2 in Bangladesh, 2 in South Africa,
2 in Yemen and 1 in Kenya. This makes it one of
the worst earthquake disasters in the 20th
century,
second only to the 1976 Tangshan earthquake
in China that claimed 2,42,000 lives.
In terms of the tsunami, it is the deadliest in recorded history and
overshadows the past tsunami disasters at
Sanriku in Japan (1896) and Lisbon
in Portugal (1755). At the time of this
ocean-wide tsunami no tsunami warning systems existed in the Indian
Ocean. At many, if not most locations, the sea
receded several metres before the first waves hit and this
was the first indication that a "tidal wave" had arrived.
This was heeded at some locations such as in Thailand and on Teresa
Island (Nicobar Islands) with people fleeing to higher ground while
alerting others. But in almost all other locations people rushed
forth to witness or photograph this strange phenomenon or to gather
dozens of fish left stranded by the retreating waters; moves that
were to prove fatal in most cases.
Magnitude
|
Earthquake Shaking |
Aftershocks
| Tsunami |
Seiches & other phenomenon
The
epicentre of this earthquake was 42 kms N
of Batunazerah (Simuelue Island),
Indonesia,
or 102 kilometres SSW of Meulaboh
(Sumatra), Indonesia,
or 257 kilometres SSE of Banda Aceh
(Sumatra), Indonesia,
or 324 kilometres W of Medan (Sumatra),
Indonesia,
or 990 kilometres SSE of Port Blair (South
Andaman Island), India,
or 1806 kilometres ESE of Colombo, Sri
Lanka,
or 2028 kilometres SE of Chennai (Tamil
Nadu), India,
or 2177 kilometres SE of Bhubaneswar (Orissa),
India.
Magnitude:
The magnitude of this earthquake was initially reported
to be Mw=8.2 by the NEIC. However, as more information was
available, this was revised upwards a few hours later to Mw=9.0
based on a Centroid Moment Tensor solution derived by the CMT
Working Group at Harvard University. Other studies done on this
earthquake have arrived upon magnitudes (Mw=9.0-9.3) in this range
and the small differences in these are due to differing assumptions
on fault geometry. The officially recognised magnitude for this
event is Mw=9.1. This earthquake is the 3rd largest
instrumented earthquake since 1900 and the strongest anywhere on the
planet since the 1964 Mw=9.2 Prince
William Sound earthquake in Alaska and the strongest during the
instrumented era in seismology i.e. 1966 to present. The largest
earthquakes in the 20th century was a Mw=9.5 that struck southern
Chile in 1960. Also, based on the recorded tide gauge data a Tsunami
magnitude (Mt) of 9.1 was calculated for this event.
Media/Press Note:
The magnitude of this earthquake should be reported/read as
"magnitude 9.1" and printed as "M9.1". Please note that this
magnitude is NOT Richter magnitude (ML) but is instead Moment
Magnitude (Mw) and therefore MUST NOT be reported as "on the
Richter Scale".
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Earthquake Shaking Effects:
The earthquake was
strongly felt in northern Sumatra and in the Indian Andaman &
Nicobar Islands i.e. along the rupture. The strongest shaking was
experienced on the island of Simuelue off the coast of Sumatra where
people were reportedly thrown to the ground by the mainshock. On
Sumatra itself, strong and damaging shaking was felt along the west
coast at places such as Kembang Cot and Meulaboh
that caused a few modern buildings to collapse. Further
inland, landslides were triggered in the Barisan Mountains and some
buildings were damaged at Takaptuan. In the larger cities of Medan
and Banda Aceh the shaking had varied effects. In Medan,
although
the quake was frightening enough to send people running outdoors and
to cracks some windows, the city fared much better than Banda Aceh
where some newer modern high-rise buildings such
as the Pante Pirak department store suffered various grades
of damage. Northward, damage to buildings was reported from the
Andaman & Nicobar Islands. In the Nicobar Islands, buildings were
damaged on the islands of Car Nicobar, Katchall and Nancowry. At
Campbell Bay on Great Nicobar Island though many of the low-rise
buildings escaped with hairline cracks some newer buildings suffered
non-structural damage. Liquefaction was observed on Car Nicobar
Island. In the Andaman Islands, damage was similar as in Indonesia,
with newer buildings suffering more damage as compared to older &
low rise structures. In Port Blair, the earthquake began as a
noticeable tremor that progressed into a strong shaking that made it
difficult to remain standing.
Farther away, to the
east the quake was felt in many parts of Malaysia, Singapore and
Thailand. he tremor was also felt in Bangkok,
Chiang Mai and other cities in Thailand. Several high-rise buildings
were evacuated in Malaysia, including at Pinang
and Port Klang. The shock was also felt at Alor Star and Pangkor.
Residents of Singapore also felt the earthquake.
To the west, the quake
was felt at several locations in peninsula India as well as in the
Bengal. Minor damage was reported form Barisal, Chandpur Sadar and
Chittagong in Bangladesh. Elsewhere in the country it was felt in
most places including the capital, Dhaka and many people were woken
up, some went outdoors. It was the strongest
earthquake to shake Bangladesh since 1988. In India, the
quake was distinctly felt along the east coast.
In Tamil Nadu, people felt distinct tremors in most parts of Chennai
as well as at Pondicherry & Tuticorin. The quake
was also felt at Bhubaneswar and in towns in the Mahanadi
delta in Orissa and many people left their homes
and went outdoors. It was also felt at Mayurbhanj, Jajpur, Koraput
and Sunabeda. Tremors were also reported from the coastal belt of
Andhra Pradesh from Srikakulam to Chittoor as well as in the cities
of Nellore, Vishakhapatnam and Vizianagaram. People in
Vishakhapatnam ran out of their homes in panic, most notably in the
East Point Colony, MVP Colony and Seethamanmadhara areas. Tremors
were also felt in Kochi in Kerala and Bengalooru in Karnataka. A few
buildings developed cracks at Bhubaneswar, Chennai and
Vishakhapatnam but there were no reports
of major damage from any parts of mainland India due to this
earthquake. In West Bengal, the quake was also felt in Kolkata.
Tremors were also felt at Dhanbad and the surrounding towns in
Jharkhand. The earthquake was also felt in high-rise
buildings at distant locations such as Ahmedabad in Gujarat and
Mumbai in Maharashtra. Many places in Sri Lanka,
such as Kandy also felt the tremors for a prolonged period.
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Aftershocks:
Several powerful aftershocks have been
reported from the region. Additional strong
earthquakes were reported from the adjoining parts of the Andaman &
Nicobar Islands within hours of this earthquake. Many of these
earthquakes occurred in or near the main islands in this
archipelago. 23 aftershocks with magnitude in excess of Mb=6.0
were recorded till 00:00 GMT on 09
January 2005. The strongest aftershock
within a week of the mainshock was a Mw=7.2
event that occurred at 09:51 AM IST on 26 December. This was centred
81 kilometres SW of Pulo Kunji in Great Nicobar Island. The
possibility of further aftershocks in this magnitude range cannot be
ruled out. A total of 25 aftershocks of M6.0 or greater occurred up
to 24 January 2005, spread over a region from Simuelue
Island (off Sumatra, Indonesia) in the south to near Landfall Island
(off North Andaman, India), in the north. These and other
aftershocks clearly delineate a 1,000+ kilometre section of the
plate boundary between the Indian Plate and the Burmese Micro-Plate
that ruptured in the mainshock on 26 December 2004. Some of the
larger aftershocks were strong enough to be felt as far as Chennai
on the east coast of India, causing panic and minor damage.
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Indian Ocean-wide
Tsunami:
A
major tsunami also struck the coast of
Aceh province shortly after the
earthquake and was reported from the towns of
Banda Aceh and Lhokseumawe.
Heavy damage and fatalities are reported from Banda Aceh and other
towns in the province of Aceh. Large sections of Banda Aceh were
destroyed in the tsunami. Satellite photos show the true extent of
the damage to the city, with large northern sections completely
wiped out. The Indonesia army and police cordoned off these sections
to survivors as they cleared away thousands of bodies. Many fishing
villages and towns such as Calang and Meulaboh, along the west coast
of Aceh province were almost completely
washed away. People are believed to have watched the water recede
and the ran to pick up fish left stranded on the seafloor while
other rushed to take photographs. The waves that followed penetrated
the coast to a great extent but in some places their force was
arrested by high cliffs along the shore.
In Sri Lanka, a wave
reported by the press as being 40-feet high struck the eastern and
southern coast. Residents of Colombo sought refuge on higher ground
in fear as coastal areas of the city were hit by the tsunami. Other
affected areas include Batticaloa, Galle, Jaffna, Matara and
Trincomalee to mention a few. A passenger train, the "Queen of the
Sea" on its way from Colombo to Galle was swept away near Telwatte
killing over a 1,000 people and other locals who clambered aboard
hoping it would save their lives. Buses and cars were washed out to
sea and numerous seaside communities like Hambantotte were heavily
damaged. Here, as in Indonesia, people were puzzled by the recession
of the water and rushed forward to view this rare phenomenon and
were then caught by the ensuing waves.
People in Trincomalee are thought to have
gathered "bag loads of colourful fish" before the tsunami made
landfall.
Many
parts of the Thailand coast were badly affected and many popular
tourist resorts like Khao Lak and Koh Phi Phi were badly hit.
Thousands of tourists vacationing in the area were among the
fatalities. At one location, a shark was found in a hotel swimming
pool once the water went down and two dolphins were also stranded in
an inland pond.
In
the Nicobar Islands, the tsunami causing widespread damage wiping
out entire villages like Campbell Bay on Great Nicobar Island and
Malacca on Car Nicobar Island. Waves
nearly 3-storeys high, devastated the Indian Air Force base near
Malacca. Satellite photographs detailed the extent of tidal
inundation in these islands with some parts of Car Nicobar and
Trinkat Islands permanently submerged. The worst affected in the
Andaman & Nicobar chain is Katchall Island. Out of a total
population of 5312, 303 were confirmed dead while 4354 were reported
missing. The islands of Camorta, Car Nicobar and Trinkat also
reported heavy human losses. In the Andaman Islands, considerable
damage was caused by the tsunami to Port Blair, leaving ships
perched atop docks and on roads. A large tidal surge also struck the
entire eastern Indian seaboard. In the city of Chennai, the surge
covered the entire breadth of Marina Beach. Cars and boats were
carried away by the torrent. Local television stations showed panic
stricken people fleeing in ankle-deep water that flooded roads along
the Marina. City landmarks like the Ashtalakshmi Temple and the
Santhome Church were also flooded. The worst affected region in
Tamil Nadu was the port city of Nagapattinam, where entire
neighbourhoods were inundated. Many pilgrims living around the
Shrine of Our Lady of HeTITLEh at Vellankani drowned. Damage was also
reported from Cuddalore, Pondicherry and Kanyakumari. Hundreds of
tourists were trapped at the Vivekananda Memorial at Kanyakumari for
several hours before being rescued. Further north in Andhra Pradesh,
tsunami damage was reported from Nellore, Machlipatinam and
Vishakhapatnam to name a few. Many people gathered at a beach near
Machlipatinam for religion ceremonies were swept away. Parts of
Vishakhapatnam were flooded causing panic among the citizens. Tidal
surges caused damage and fatalities parts of coastal Kerala, the
worst being in Kollam. Tidal surges were also reported from
Mangalore and Suratkal in Karnataka and all along the Goa coast
including the city of Vasco. Minor damage was reported from the
coast of Maharashtra, most notably in the region of Ratnagiri and
Sindhudurg areas where coastal flooding and strong currents swept
away boats and inundated a few coastal roads and houses. Noticeable
but less energetic surges were also experienced in Mumbai. Waves
were also reported from Orissa and West Bengal but did not cause any
damage. Eyewitnesses also stated that the sea first receded leaving
the sea bed exposed for a few moments, during which children and
adults alike rushed to gather fish left stranded.
The
tsunami struck the Maldives killing many
people and submerging many buildings in the
capital, Male. The tsunami also struck Malaysia. Tsunami activity
was also reported from Burma where many buildings and bridges were
damaged in the town of Kawthaung as well as elsewhere along the
coast.
The
Australian Cocos Islands were also hit by a half metre tsunami and
the coast of Western Australia experienced significant but
non-destructive tsunami activity. Surges inundated coastal areas of
Oman and a few people were injured in 5-metre waves that hit the
Maharah region. Tsunami activity was also reported from East Africa.
Tsunamis capsized boats in the Puntland region of Somalia and many
fishermen were washed away. Further south in the Seychelles,
fatalities were reported and the town of Mahe was reportedly
flooded. In Kenya, one person was killed and many missing in Malindi
and beaches were closed in Mombasa. Rodrigues Island and beaches on
north Mauritius were flooded. The French administered, Reunion
Island, also boats in harbours sustained some damage. In
Zanzibar near Tanzania, hotel guests were evacuated to higher
ground. A half a metre wave was also recorded a Port Elizabeth in
South Africa. Other locations such as Durban Harbour also recorded
unusually strong currents. More than 1200 people were left homeless
by the waves on the east coast of Madagascar. Tide gauges in
countries around the Pacific rim also recorded minor wave activity.
Such activity was recorded as far as Alaska, Hawaii and San Diego in
the United States, Callao and Inquique in Chile and as well as New
Zealand, Fiji, Vanuatu and American Samoa. In Mexico, 8-foot waves
were reported at Manzanillo.
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Seismic
Seiches & Other Phenomenon:
This
earthquake also caused energetic seismic
seiches in water bodies in Assam,
Jharkhand, Maharashtra, Manipur, Orissa and West Bengal. In Kolkata,
residents of Behala in the south-eastern part of the city describe
vigorous seiches in ponds in the area. Seismic seiches
were also seen in other parts of Kolkata and also in Balasore in
neighbouring Orissa. One person drowned in a pond as a result of a
seiche in Nadia, West Bengal. Television news reports also said such
instances were common in Bhubaneswar, Balasore, Puri and other towns
in Orissa. Press reports from Jharkhand also spoke of similar
occurrences in Dhanbad and Rajganj. Similar phenomena were
observed throughout Bangladesh and at the Maipokhari Lake in eastern
Nepal as well as from water bodies in northern Thailand.
A seismic seiche was
also reported from ponds in the Ganeshpuri temple and from Gorai in
Mumbai in Maharashtra.
Such seiches were reported from the almost same region in the last
great Mw=8.5-8.7 earthquake in
Sumatra in 1861.
Eruptions of natural gas that ignited along with eruptions of mud
volcanoes were reported from locations along Burma's Arakan coast
and also in Sandoway. A mud volcano, Barren 1, erupted on the
uninhabited Baratang Island in the Andamans. This must not be
confused with the very different, Barren Island volcano.
Some press reports also
claimed that both, the Barren Island and the Narcondam volcanoes
were erupting but these have since been proved to be baseless.
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